Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <stdio.h>
#define inf 999999999
int main(){
    int h,w,cost[52][52],cnt;
    char s[52][52];
    scanf("%d%d",&h,&w);
    for(int i=1;i<=h;i++) scanf("%s",s[i]+1);
    for(int i=0;i<52;i++) for(int j=0;j<52;j++) cost[i][j]=inf;
    cost[1][1]=1;
    for(int k=1;cost[h][w]==inf;k++){
        cnt=0;
        for(int i=1;i<=h;i++) for(int j=1;j<=w;j++){
            if(cost[i][j]==k){
                cnt++;
                if(s[i-1][j]=='.'&&cost[i-1][j]>k)cost[i-1][j]=k+1;
                if(s[i][j-1]=='.'&&cost[i][j-1]>k)cost[i][j-1]=k+1;
                if(s[i+1][j]=='.'&&cost[i+1][j]>k)cost[i+1][j]=k+1;
                if(s[i][j+1]=='.'&&cost[i][j+1]>k)cost[i][j+1]=k+1;
            }
        }
        if(cnt==0){
            printf("-1\n");
            return 0;
        }
    }
    cnt=0;
    for(int i=1;i<=h;i++) for(int j=1;j<=w;j++) if(s[i][j]=='.') cnt++;
    printf("%d\n",cnt-cost[h][w]);
}